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8 Cygni 
Summary
8 Cygni is a single[7] star in the northern constellation of Cygnus. Based upon its parallax of 3.79 mas,[1] it is approximately 860 light-years (260 parsecs) away from Earth. It is visible to the naked eye as a faint, bluish-white hued star with an apparent visual magnitude of about 4.7.[2] The star is moving closer to the Earth with a heliocentric radial velocity of −21 km/s.[4]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 19h 31m 46.32184s[1] |
| Declination | +34° 27′ 10.6874″[1] |
| Apparent magnitude (V) | 4.75[2] |
| Characteristics | |
| Spectral type | B3 IV[3] |
| B−V color index | −0.155[2] |
| Astrometry | |
| Radial velocity (Rv) | −21.20±0.1[4] km/s |
| Proper motion (μ) | RA: 1.16[1] mas/yr Dec.: −3.47[1] mas/yr |
| Parallax (π) | 3.79 ± 0.16 mas[1] |
| Distance | 860 ± 40 ly (260 ± 10 pc) |
| Details | |
| Mass | 6.40[5] M☉ |
| Radius | 6.50[5] R☉ |
| Luminosity | 2,512[5] L☉ |
| Surface gravity (log g) | 3.62[5] cgs |
| Temperature | 16,100[5] K |
| Metallicity [Fe/H] | +0.25[5] dex |
| Rotational velocity (v sin i) | 15[6] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is an aging subgiant star, as indicated by its spectral type of B3IV.[3] Its effective temperature of 16,100 K fits into the normal range of B-type stars: 11,000 to 25,000 K. 8 Cygni is about twice as hot as the Sun, and it is six times larger and many times brighter in comparison.[5] The elemental abundances are near solar.[8]
References edit
- ^ a b c d e f van Leeuwen, F.; et al. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
- ^ a b c Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
- ^ a b Lesh, Janet Rountree (December 1968), "The Kinematics of the Gould Belt: an Expanding Group?", Astrophysical Journal Supplement, 17: 371, Bibcode:1968ApJS...17..371L, doi:10.1086/190179
- ^ a b Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
- ^ a b c d e f g Challouf, M.; et al. (2014), "Improving the surface brightness-color relation for early-type stars using optical interferometry⋆", Astronomy & Astrophysics, 570: A104, arXiv:1409.1351, Bibcode:2014A&A...570A.104C, doi:10.1051/0004-6361/201423772, S2CID 14624307.
- ^ Abt, Helmut A.; Levato, Hugo; Grosso, Monica (2002). "Rotational Velocities of B Stars". The Astrophysical Journal. 573 (1): 359–365. Bibcode:2002ApJ...573..359A. doi:10.1086/340590.
- ^ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
- ^ Adelman, Saul J. (June 1998). "Elemental abundance analyses with DAO spectrograms - XIX. The superficially normal B stars zeta Draconis, epsilon Lyrae, 8 Cygni and 22 Cygni". Monthly Notices of the Royal Astronomical Society. 296 (4): 856–862. Bibcode:1998MNRAS.296..856A. doi:10.1046/j.1365-8711.1998.01426.x.